This relates generally to electronic devices and, more particularly, to electronic devices with displays.
Electronic devices often include displays. The overall brightness level of many displays is adjustable. For example, a display may have a brightness setting that can be increased or decreased manually by a user. A display might also have a brightness setting that is automatically adjusted in response to ambient light measurements. With this type of automatic brightness level control, the display can be automatically made brighter when ambient lighting conditions become bright to help ensure that the display remains visible to the user.
To ensure that displays do not consume too much power and to help enhance display longevity, electronic devices often use a peak luminance control algorithm (sometimes referred to as automatic current limiting).
When peak luminance control functionality is enabled, the peak luminance of displayed images is reduced whenever the content being displayed exhibits large values of average frame luminance. This ensures that the amount of current and therefore the amount of power that is drawn by the display will be capped. In addition to limiting power consumption, this may help limit temperature rise in the display and thereby extend the lifetime of display pixels in the display.
When the average luminance of a frame of image data is low, the display is allowed to display content with a large peak luminance. In this situation, a display with sparse content such as a few icons on a black background can display the content brightly.
Challenges arise when using a device that has an adjustable display brightness setting and a simultaneously active peak luminance control algorithm. As an example, in dim lighting conditions or other situations in which the brightness setting is low, the use of a peak luminance control algorithm that further reduces luminance upon detection of frames of data with high average luminance may reduce luminance so much as to make it difficult or impossible to view content on the display.
It would therefore be desirable to be able to provide improved ways in which to handle brightness settings and peak luminance control operations in a display.